About to begin bidding process. Words of wisdom?

We are working with an architect on a big renovation project of a land-marked house. (It is not a gut) We are about to start the bidding process. I realize that the quote is only part of the decision factors. What questions would you ask of the bidding contractors? Any other advice from btdt.. what would you have done differently? what did you like? Our big worry is time, as we will have to move out during the renovation.